The present invention generally relates to surgical instruments for performing laparoscopic and endoscopic surgical procedures, and, more particularly, relates to a self-retaining cannula assembly incorporating a novel retention mechanism for securing the cannula within an incision in a patient""s body while preventing over insertion of the cannula during application.
In laparoscopic and endoscopic surgical procedures, a small incision or puncture is made in the patient""s body to provide access for a tube or a cannula device which is inserted into the patient""s body to permit for viewing of the surgical site or for the insertion of instruments used in performing the surgical procedure. Typically, a trocar device is used to penetrate the body wall, whereby a sharpened point or tip of the trocar assembly creates the path to the surgical site. A cannula is provided as part of the trocar assembly such that when the pointed piercing mechanism is removed, the cannula remains in place to maintain access to the surgical site. Several incisions may be made to provide numerous access ports to the surgical objective, and once the cannulas are in place, various surgical instruments such as scissors, dissectors, retractors or the like, may be inserted by a surgeon to perform the surgery. Typically, a scope device is used to view the area directly, or a miniature camera is used to display the surgical site on a video monitor in the operating room.
In order to maintain the cannula within the incision, it has been known to provide various mechanisms such as external sleeves, expandable members, etc. which engage the tissue surrounding the incision to prevent undesired removal of the cannula. However, such known mechanisms are generally complex in nature. Moreover, these mechanisms often are potentially invasive to the surrounding tissue thereby increasing the likelihood of undesired tissue tear which consequently increases patient trauma and recovery time. Another deficiency in known cannulas of this type concerns the lack of structure to prevent over insertion of the cannula during application within the surgical site.
Accordingly, the present invention is directed to a cannula including a novel tissue gripping arrangement which supports the cannula in an incision in the patient""s body to provide access to the abdominal cavity during, for example, a laparoscopic or endoscopic surgical procedure. In a preferred embodiment, the cannula includes tissue gripping elements which are arranged to facilitate insertion of the cannula within the cavity by, for example, minimizing insertion force required to advance the cannula relative to the operative site while also restricting removal of the cannula by increasing the withdrawal force required to remove the cannula. Furthermore, several of the tissue gripping elements are specifically adapted to engage the tissue upon insertion of the cannula a predetermined distance to thereby minimize the potential of overinsertion of the cannula relative to the operative site thereby avoiding potential consequences to underlying tissue, organs, etc. Several embodiments of the cannula with the tissue gripping elements are disclosed.